THE 


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GEOLOGY AND METALLURGY 

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BEING A REPORT ADDRESSED TO THE 



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ET 


J. W. FOSTER. 


IRON.—“ Every one knows the manifold uses of this truly precious metal. It is capable of 
being cast into moulds of any form ; of being drawn into wires of any desired strength or 
fineness; of being extended into plates or sheets; of being bent in any direction; of being 
sharpened, hardened, and softened at pleasure. It accommodates itself to all our wants, our 
desires, and even our caprices. It is equally serviceable in the arts, the sciences, to agriculture, 
and war : the same ore furnishes the sword, the ploughshare, the scythe, the priming-hook, the 
needle, the graver, the spring of a watch or of a carriage, the chisel, the chain, the anchor, 
the compass, the cannon, and the bomb. It is a medicine of much virtue, and the only metal 
friendly to the human frame.”— Dr. Ure. 


Oft 7-337^ i/zf/feU'cL 

NEW YORK: 

WM. C. BRYANT & CO., PRINTERS, 41 NASSAU STREET, CORNER OF LIBERTY. 

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Chicago, Feb. 6, 1S65. 


To the Directors of the 

Iron Cliffs Company, 

12 Wall St., New York: 

Gentlemen ,—I submit to you a report on the mineral resources of the lands 
belonging to this Company, comprising more than 37,000 acres, in the heart 
of the Iron Region of Lake Superior, in the State of Michigan. 

These lands are covered by a primeval forest. It is only within the past 
year that they have been intersected with roads and rendered accessible 
to settlement. Explorations, under such circumstances, and prosecuted as 
they have been but for a few months, cannot be expected to reveal but a 
portion of the metallic wealth ; enough, however, is known to give the assur¬ 
ance that these lands are abundantly stocked with iron ores, and of sufficient 
purity to compete with the best ores of the region. 

With the exception of Rivot’s “ Notice sur le lac Superieur ,” (Paris, 1857,) 
little of a permanent character has been added to our knowledge of this region, 
since the publication of the report of Mr. Whitney and myself in 1851. Since 
then, the Iron interest has assumed proportions of magnitude little dreamed 
of by those who 'witnessed its infancy; and marvelous as has been its past 
growth, its future promises to be still more so. 

As this Company and the allied Company—the Peninsula Railroad—have 
a deep interest not only in the mining, but in the transportation of these ores, 
and as many of the shareholders are largely the consumers of them, I have 
felt at liberty in this report to go beyond mere local details of explorations :— 
to treat of their geology and analogies to deposits in other regions of the 
globe; of their chemical properties, and the metallurgical processes to which 
they should be subjected; of their commercial value, of the cost of mining 
and transportation, and of prospective demand and supply. 

I am, with great respect, 

Your ob’t serv’t, 


J. W. POSTER. 







































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PART I. 



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REPORT. 


GEOLOGY OF THE IRO N ORES, 

GEOGRAPHICAL POSITION. 

The Peninsula of Lake Superior, while on the verge of culti¬ 
vable lands, is abundantly rich in local resources. Though not 
“ a land of wheat and barley,”—such as was promised by the 
Jewish lawgiver to his people—it is “ a land whose stones are 
iron, and out of whose hills thou rnayest dig brass.” On every 
side it it is accessible to commercial intercourse. The two great 
lakes, Superior and Michigan, gird it on the north and on the 
south, with shore lines exceeding 600 miles in length. Kewee¬ 
naw Point, the seat of the Copper Pegion, is in the form of a 
bended bow—a similitude recognized by the early Jesuit ex¬ 
plorers ; while the Iron Pegion, occupying a long, narrow belt, 
may be likened to the cord of the bow. 

On the west, the Mississippi, flowing with a turbid current to 
the Gulf of Mexico, with its affluents almost interlocks with 
those of the St. Lawrence ; and from the earliest history of the 
region to the present hour, the voyageur, in his light canoe, has 
been accustomed to pass, with slight impediment, from one river 
system to the other. 

On the east, the St. Mary’s Piver, flowing out of Lake Su¬ 
perior through a broad channel, before reaching Lake Huron, 
looses itself amid ten thousand islands, whose rocky banks and 
wooded slopes were, in the Indian mythology, the residence of 
the Great Maniton, whose name they have retained, and whose 
watchful care was exercised in keeping these straits free from 
all profane intrusion. 


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On tlie south, Bay de3 Roquets, penetrating for fifteen miles 
inland, affords a harbor ready of access, sheltered from every 
wind, and capacious enough to ride the fleets of all the lakes. 
Their tideless waters preserve a nearly unvarying depth, so that 
vessels may receive and discharge their cargoes while lying at 
the wharves. 

The watershed between the two lakes and embracing the 
Iron Region, attains an elevation of nearly 1,200 feet; but the 
engineer, availing himself of the depressions of the country, need 
not rise higher than 800. The crest occurs within 12 miles of 
Lake Superior, and 60 miles from Lake Michigan. 

The Peninsula Railroad Company, availing themselves of this 
natural configuration of the ground, have constructed a railway 
up the southern slope from Bay des Roquets to the Iron Region, 
with long reaches of straight line, and with descending grades 
of about 15 feet to the mile, so that the ability to transport 
loaded trains is only limited by the power of the locomotive to 
take back the empty cars. 

The Marcpiette and Bay de Roquets Railroad, which for 
many years has been in successful operation, climbs the northern 
slope by making use of abrupt curves and steep grades, one of 
which exceeds 170 feet to the mile. 

The creation of an additional outlet on Lake Michigan will 

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increase two-fold the traffic of the region, and give employment 
to 150 additional vessels. 


AREA OF TIIE IRON ORES. 

There is no region of the earth where the ores of iron are 
developed on a scale of such grandeur, or concentrated in such 
a state of purity as on the southern shore of Lake Superior. 
Dannemora, Rijny Tagilsk, Elba, or Missouri, may contain 
isolated deposits equally rich ; but these combined would occupy 
a mere patch on the surface over which the ores of this region 
are known to be distributed. 

This area is somewhat irregular in outline; its length, east 
and west, is about 150 miles, with a variable width, north and 
south, ot from 6 to 70 miles ; but the greatest concentration of 
these ores thus far observed, is in Township 47 north, Ranges 
26, 27, and 28 west. 


GEOLOGY OF THE DISTRICT. 


The Iron Ee gion consists of an assemblage of rocks of various 
kinds, such as argillite, talcose, chlorite, and hornblende 
schists, quartzites, and occasionally dolomites, all of which are 
supposed to be of metamorphic origin, intermingled with rocks 
whose igneous origin can hardly be doubted, consisting of the 
various compounds of felspar and hornblende, forming green¬ 
stone or dolorite; or where silica abounds, forming syenite; or 
serpentine, where magnesia is in excess. 

The region is bounded both on the north and on the south by a 
series of crystalline rocks, in which granite largely predominates. 

The general direction of the formation is east and west, 
though subject to minor deviations, and the culminating points, 
which consist for the most part of greenstone, attain an eleva¬ 
tion exceeding 1,100 feet above the lake. The metamorphic- 
rocks exhibit a regularly contorted structure, and, wherever they 
approach the purely sedimentary rocks, arc found to be over¬ 
laid by the Potsdam sandstone, whose strata repose in a nearly 
horizontal position. 


MODE OF OCCURRENCE OF TIIE IRON ORES. 


It may be stated, as a general rule, that the great iron deposits 
of the district occur in close proximity to the igneous rocks, 
mainly greenstone. This rock forms nearly all of the prominent 
peaks of the region, not in continuous ranges, but in a succession 
of dome-shaped knobs, while the iron ores repose upon their 
sides or dip beneath their bases, so that* the greenstone appears 
rather in the form of intercalated beds than as wedge-shaped 
masses. 

The whole region has been subjected to a powerful denuda¬ 
tion, and the greenstone being the more unyielding rock, has 
been left ip the form of knobs or of ill defined ridges. I cannot 
recall an instance where it forms a true axis of elevation. 

The beds of iron ore often attain a thickness of four or five 
hundred feet, and maybe traced longitudinally for five thousand 
feet, but they are far from being persistent in character. The 


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quartzose materials so abound that it is only in pockets, or 
lenticular bands, that the highly concentrated ores are found. 
This is seen at all of the mines which have been extensively 
worked, and the necessity of sinking below drainage has already 
arisen, and preparations have been made to meet it, by driving 
adits and by erecting pumping machinery. 

OKES OF IKOX. 

The iron ores of this region may be arranged under the 
following heads: 

1. Magnetites. 

2. Red Haematites. 

<% 

3. Brown Hematites. 

4. Manganesiferous Ores. 

5. Argillaceous Ores. 

1. Magnetite , Magnetic Oxide of Iron. —This, when pure, 
yields 72.41 per cent, of iron, and is a protoxide consisting of 
28 iron, S oxygen=36.5. sp. gr., from 4.9 to 5.2. It may be dis¬ 
tinguished from the other ores of iron by giving a black streak. 

Tims far no mines of this ore have been developed, but it 
exists on the borders of Machigummi, and I have seen quite 
pure specimens from St. Clair Mountain. 

Extensive beds exist on the Company’s lands in Section 18, and 
the northeast quarter of Section 19, Township 47 north, .Range 26 
west; also, on the south half of Section 13, and on Section 24, 
Township 47 north, Range 27 west. These ores have a slaty 
cleavage and much disseminated silica; yet there is reason to 
believe that, on exploration, they will be found sufficiently con¬ 
centrated to prove merchantable. 

2. Red Hematites , or anhydrous Sesquioxides .—These are 
the predominant ores of the region. When pure they yield 70 
per cent, of iron, the formula being, 28 iron, 12 oxygen = 40. 
sp. gr. 5.1 to 5.2. They may be recognized by their red streak. 
At all of the working mines we meet with the two varieties of 
specular and micaceous, and in most specimens can be detected 
disseminated crystals of magnetic oxide—so that these ores are 
in fact, a union of the two. 


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At tlio Jackson Mine, there is a belt of earthy haematite, 
which contains numerous cavities, often lined with brilliant 
black acicular crystals, also exhibiting botryoidal forms. Some 
of these crystals are hydrated, and in this connection occurs the 
mineral goetheite. This ore is peculiar to this mine. 

At the Tilden Mine, in places, the ores are very dense. They 
break with a steel-like fracture, and are cut, at intervals of an 
inch or so, by divisional planes; at other jpoints the red oxides 
occur studded with minute and sparkling crystals. This is also 
the character of the ore on the southeast quarter of Section 22, 
Township 47 north, Range 27 west, on the Company’s lands. 
On Section 12, Township 47, Range 27, the ores are earthy; 
the same is true, to some extent, of the ores of the Ogden 
Mine, though portions may be classed as red oxides, with evi¬ 
dences of the hydrates and magnetites. 

3. Brown Hematite, or hydrated sesqiiioxide of Iron .— 
This ore, when pure, yields 59.89 per cent, of iron, and 14.44 of 
water. The specific gravity is 3.5. This ore can be readily 
distinguished by its yellowish or brownish streak. Nothing 
analogous to the haematites which occur on the Company’s 
lands, at the Foster Mine, have been found elsewhere in the 
district. They appear to occupy quite an extensive area, and 
to form a part of the rock structure of the region. 

Their mode of occurrence is : 

1. In the form of gravel beds of uifexplored depth, the result 
of decomposition of the ores in situ , and not of aqueous 
deposition. 

2. In masses intermediate between the red and brown oxide 
(hydrous and anhydrous). 

3. In large tabular plates, like a bundle of wheat straws, 
or the sejotoe of honey-comb. 

4. In masses of a porous structure. 

5. In mammillary concretions, in radiating groups, and other 


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forms—all of these varieties often exhibiting the external 
lustre of freshly melted copper. This polish is unctuous to 
the touch, adheres to the fingers, and would make a good 
pigment. The compact and vesicular varieties, with silica 
disseminated in the form of colorless quartz, are found in 
this association. 

The ochreous brown haematites, known as bog-ores or 
limonites, occur in the vicinity of Grand Island, and on 
the borders of the Maniste River, but they have not 
been wrought. This class is the most impure of all ores, 
containing sulphur and phosphorus to such an extent as to 
render the iron made from it fit only for castings, 
bombs, weights, &c., and it will not therefore form a mer¬ 
chantable ore from this district. 

4. Manganesiferous Iron Ore .— This occurs in a considerable 
body on the northeast quarter of Section 12, Township 47, 
Range 27, in connection with the haematites. 

5. —Argillaceous Ores .—The ores on the northeast quarter of 
Section 19, Township 47 north, Range 26 west, and also those of 
the Ogden Mine, while they have the external characters of a 
compact red haematite emit, when breathed upon, a strong ar¬ 
gillaceous odor. They are sufficiently rich to form workable 
ores, yielding from 50 per cent, to 65 per cent, of metallic iron. 


LOCALITIES OF IKON OEE ON THE COMPANY’S LANDS. 

With our present knowledge of these lands, it is to be pre¬ 
sumed that we know very little of the metallic wealth which 
they contain. Even of the known deposits, few have been sys¬ 
tematically explored, and I have information as to the existence 
of others which I have been unable personally to inspect. 

The-explorations in the future will undoubtedly prove as suc¬ 
cessful as in the past. 

Enough, however, is known to give the assurance that these 
lands contain a combination of ores not before observed in the 
district, of great purity, exhaustless in quantity, and most favor¬ 
ably situated for mining and smelting. 


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The known localities are indicated on the accompanying map 
by the appropriate symbol for iron. 


Township 47, Tange 27, Section 5, Southwest Quarter. —A 
low ridge, bearing east and west, is observed on the north side 
ot Lake Corning, which is charged with red oxide of iron. 
While there may be obtained very good hand specimens, the 
great mass is too much intermixed with quartzose materials to 
make it of much commercial value. 


Township 47, Tange 27, Section 8.—Near the centre «of the 
section there is a drift : covered ridge, running east and west, 
which rises to the height of 70 feet above the Carp River. 
Near the base and high up the slope are seen large angular 
blocks of specular ore, which appear to have been detached 
from a concealed ledge near by. Some of these masses are 4 
and 5 feet in diameter and G and 8 feet lone:. In digging about 

ZD 05 O 


them, however, they are found to be detached. The angularity 
of these blocks, their magnitude, and the fact that they are not 
in the direction of the great drift current, whicli has swept over 
this region, induce me to believe that the parent bed will be 
found in close proximity. 

The ore displayed in these blocks is of the specular variety, 
and in purity is equal to any deposit in the district. 


Township 47 North , Tange 27 West, Section 9, Northeast 
Quarter. —This tract abuts on the Lake Superior Company's 
mine, and exploitation has been carried on by that Company to 
within a few rods of the line. The ground for the most part is 
low and drained by a branch of the Carp River. On the south 
side, however, there is a triangular tract of about ten acres, 
which rises 40 or 50 feet above the stream, the surface of which 
is drift-covered, consisting of loose sand and gravel. Test pits 
have been sunk, and ore was struck at a depth varying from 10 
to 1G feet. The low region to the north of the stream will 
afford a desirable dumping ground, while on the south a breast 
of 40 feet can be obtained above natural drainage. 



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The ore revealed by these explorations is of the very best 
quality—specular in appearance, coherent enough to bear trans¬ 
portation, and readily crumbles under the drill. I have little 
doubt that a first-class mine, though of limited area, can be 
here developed. 

Township 47, Range 27, Section 12.—This tract adjoins the 
Jackson Co.’s location on the south, and contains large deposits 
of ore, occupying the depressions between the ridges of green¬ 
stone. 


MANGANESIFEROUS IRON ORES. 

» 

On the northeast quarter of the northeast quarter of this 
section there is a bed of red haematite peculiarly rich in man¬ 
ganese, certain portions of it passing into the mineral known 
as pyrolusite. A trench, extending from the section corner in 
a west-southwest direction, has laid bare the bed for the di¬ 
stance of 200 feet. The ore is of a fair quality, but is inter- 
stratified with quartzose bands, so that, per se, it would not 
compete with the rich specular ores which occur in this vicinity. 
But it has qualities of a higher value for admixture with the 
specular ores, for the purpose of steel-manufacture; and I con¬ 
fidently believe that it will, sooner or later, be explored and 
mined in this connection. 

Three assays have been made to determine the percentage of 
manganese: 

O 


I. By Dubois and Williams, o 

II. By Prof. Geo. J. Brush, o 

III. By Jos. C. Kent, of the 
the following results: 

I. 

Iron,.41.835 

Benoxicle ) Q1 Q - a 

of Manganese, \ * * * ' 1 


J Philadelphia; 


f New Haven ; 


Cooper Iron Works; 

and w 

IT. 

III. 

4.20 

35.00 

nearly all, 

v / 

38.00 


OTHER LOCALITIES OF IROX ORE. 

On the northwest quarter of the northwest quarter of this 
section, flanking a high ridge of greenstone on the south, and in 


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the bed of a stream which crosses the road, is seen a body of 
iron ore of a fair quality for local consumption, but not suffi¬ 
ciently rich for exportation. The explorations, however, are of 
a superficial character, being limited to one or two test pits. 

The intervening valleys, formed by high ridges of greenstone, 
which rise up near the centre of the section and bear north¬ 
west and southeast, appear to be underlaid by beds of slaty 
iron ore, which occasionally crop out in escarpments one hundred 
feet in height; but I have nowhere seen the slate-iron in suffi¬ 
cient purity to authorize mining. 

TnE DUNLAP MINE.* 

In the northwest quarter of the southwest quarter of this sec¬ 
tion a knob of greenstone rises up to the height of 170 feet, 
overlooking one of those beautiful inland lakes so characteristic 
of this region. From the eastern border of this lake to within 
20 feet of the summit of the hill the predominant rock is 
iron ore. I caused a trench to be excavated across this belt 
for 310 feet, to the top of the plateau, 60 feet above the valley. 
Six hundred feet to the south another trench was started, and 
along its whole course similar beds of ore were revealed, thus 
proving its continuity between the two points; and, from the 
outcrops observed at other points, I have little doubt that this 
bed is at least 1,200 feet long, and 300 feet broad. 

The dip of the ore bands is to the southward, at an angle of 
35°, at the base of the plateau, but becomes greater as we 
ascend to the summit, where it attains 65° or 70 Q . The ore, 
when breathed upon, emits an argillaceous odor, and at the 
same time gives sparks under the hammer; and portions of it 
are intersected by bands of chert. It is very close-grained, 
generally earthy, but sometimes sub-metallic in lustre. 

I caused specimens of the ores to be collected at intervals of 
every ten feet, in a linear direction, across the outcrop, which, 
in the subjoined section, I have endeavored to group according 
to their varying characters. The specimens, characteristic of 


* In honor of Geo. L. Dunlap, Esq., Superintendent of the Chicago & North 
Western Bailroad. 





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the groups, were assayed by J. C. Draper, Professor of Analy¬ 
tical Chemistry in the University of New Pork, and his results 
are combined in this report. 

1. Proceeding from north to south, the first thirty feet consists of an earthy 

ore, somewhat argillaceous, which yields 49.7 per cent, of metallic iron. 

2. Prom 30 to 80 feet, there are intercalated bands of jasper, which render 

the ore worthless. 

3. From SO to 100 feet, the ore is very similar to the first described belt, 

yielding- 40.85 per cent. 

4. From 100 to 100 feet, the jaspery bands predominate—similar to No. 2. 

5. From 160 to 210 feet, the ore is very close grained, of high-specific gravity, 

of a bluish tinge, often sub metallic in lustre, and giving sparks under 
the hammer. Yield, 59.85 per cent, metallic iron. 

6. From 220 to 250 feet, the ores are compact, of a reddish tinge, and some¬ 

what aluminous, giving, on analysis, 59.80 per cent, of metallic iron. 

7. From 260 to 300 feet, there are alternations of the bluish and reddish 

ores, like groups 5 and 6. 

8. At 300 feet, the ores become highly siliclous, and are covered with 4 or 5 

feet of drift; and at a distance of say 150 feet, there occurs a high ridge 
of greenstone, which bounds its southern range. 


There is here a belt of iron-ore, as disclosed by those explora¬ 
tions, not less than SO feet broad, which, at the surface, yields 
about GO per cent, of metallic iron ; and which, when penetrated 
beyond atmospheric agents, will probably be found to be still 
richer. It lies within one mile of the Peninsula Railroad, and 
the intervening country is nearly a dead-level. A track might 
be laid to sweep the base of the mine for a distance of more 
than GOO feet, and the little lake near by will serve as a perma¬ 
nent reception for all of the refuse of the mine. 



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